Avishai Henik

Bio: Avishai Henik is an academic researcher from Ben-Gurion University of the Negev. The author has contributed to research in topics: Stroop effect & Numerosity adaptation effect. The author has an hindex of 61, co-authored 294 publications receiving 11785 citations. Previous affiliations of Avishai Henik include University of Oregon & University of California, Davis.

Suppression situations in psychological research : definitions, implications, and applications

Abstract: In 1941, Horst noticed that a variable can be totally uncorrelated with the criterion and still improve prediction by virtue of being correlated with other predictors. He christened such variables suppressors, a title that implies that such variables suppress criterion-irrelevant variance in other predictors. During the 50 years that have passed since Horst's original analysis, the concept of suppression has been extended and reanalyzed. What follows provides a general approach to the analysis of suppression situations. This approach is based on coupling the analysis of 3 variate suppression situations with the applications of the concept of suppressor to the general linear model. The implications of the analysis are discussed, and some applications of the concept of suppression are provided.

Is three greater than five: The relation between physical and semantic size in comparison tasks

Abstract: In this study, subjects were asked to judge which of two digits (eg, 3 5) was larger either in physical or in numerical size Reaction times were facilitated when the irrelevant dimension was congruent with the relevant dimension and were inhibited when the two were incongruent (size congruity effect) Although judgments based on physical size were faster, their speed was affected by the numerical distance between the members of the digit pair, indicating that numerical distance is automatically computed even when it is irrelevant to the comparative judgment being required by the task This finding argues for parallel processing of physical and semantic information in this task When two multidimensional stimuli are compared along one dimension, irrelevant aspects of the stimuli may intrude and influence the decision This suggests an inability to ignore or filter information even when it is irrelevant It is important to know how the filtering of an irrelevant dimension depends upon the similarity of its processing to that required for the relevant dimen­ sion Some dimensions are physical (eg, size, color); others are based on stored semantic information (eg, numerical value) Mental comparisons often involve both physical and semantic dimensions Manipulation of both physical and semantic dimensions as relevant or irrelevant to the comparison should help define how they interact Furthermore, when a dimension such as size or value is being processed, the information extracted can be crude (eg, large or small) or fine­ grained We wish to find out how detailed the processing of the irrelevant dimension is In order to study these questions, we manipulated both the numerical and physical size of digits in comparative judgment tasks The stimuli in our study were pairs of Arabic numerals We manipulated the physical size (ie, height) and the semantic magnitude (ie, numerical value) of the stimuli Each pair of digits could be characterized as congruent, incongruent, or neutral In a congruent pair, the physically larger digit was also numerically larger (eg, 53) In an incongruent pair, the physically larger digit was numerically smaller (eg, 5 3) Neutral stimuli were those in which the two digits were the same on the irrelevant dimension (eg, the pair 53 can be

From "sense of number" to "sense of magnitude": The role of continuous magnitudes in numerical cognition.

Abstract: In this review, we are pitting two theories against each other: the more accepted theory, the number sense theory, suggesting that a sense of number is innate and non-symbolic numerosity is being processed independently of continuous magnitudes (e.g., size, area, and density); and the newly emerging theory suggesting that (1) both numerosities and continuous magnitudes are processed holistically when comparing numerosities and (2) a sense of number might not be innate. In the first part of this review, we discuss the number sense theory. Against this background, we demonstrate how the natural correlation between numerosities and continuous magnitudes makes it nearly impossible to study non-symbolic numerosity processing in isolation from continuous magnitudes, and therefore, the results of behavioral and imaging studies with infants, adults, and animals can be explained, at least in part, by relying on continuous magnitudes. In the second part, we explain the sense of magnitude theory and review studies that directly demonstrate that continuous magnitudes are more automatic and basic than numerosities. Finally, we present outstanding questions. Our conclusion is that there is not enough convincing evidence to support the number sense theory anymore. Therefore, we encourage researchers not to assume that number sense is simply innate, but to put this hypothesis to the test and consider whether such an assumption is even testable in the light of the correlation of numerosity and continuous magnitudes.

Controlling Stroop effects by manipulating expectations for color words.

Abstract: An important characteristic of automatic processing is its uncontrollability. The Stroop phenomenon is regarded as a prototypical example of this characteristic of automatic processing, hence, the Stroop effect should not change when the percentages of color words versus neutral stimuli are manipulated to induce controlled processing. We found that Stroop interference decreased as the percentage of color words increased. Furthermore, the magnitude of the inhibitory component of the Stroop effect was negatively correlated with the percentage of color words; the facilitatory component was insensitive to the manipulation. These results suggest that the Stroop effect is controllable (see Logan, 1980) and that the locus of control is postlexical. The results also suggest that facilitation and inhibition are produced by different mechanisms and challenge those models of the Stroop phenomenon (e.g., Cohen, Dunbar, & McClelland, 1990; Phaf, Van der Heijden, & Hudson, 1990) that assume that a single processing mechanism causes facilitation and inhibition and that control affects facilitation and inhibition alike (Logan, 1980).

Competition Between Endogenous and Exogenous Orienting of Visual Attention

Abstract: The relation between reflexive and voluntary orienting of visual attention was investigated with 4 experiments: a simple detection task, a localization task, a saccade toward the target task, and a target identification task in which discrimination difficulty was manipulated. Endogenous and exogenous orienting cues were presented in each trial and their validity was manipulated orthogonally to examine whether attention mechanisms are mediated by separate systems and whether they have additive and independent effects on visual detection and discrimination. The results showed that each orienting mechanism developed its typical and independent effect in every case except for the difficult identification task. A theoretical framework for understanding the relationship between endogenous and exogenous orienting of attention is proposed, tested, and confirmed.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

An integrative theory of prefrontal cortex function

Abstract: ▪ Abstract The prefrontal cortex has long been suspected to play an important role in cognitive control, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery. Here, we propose that cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the flow of activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task. We review neurophysiological, neurobiological, neuroimaging, and computational studies that support this theory and discuss its implications as well as further issues to be addressed

Mediation in experimental and nonexperimental studies: New procedures and recommendations.

Abstract: Mediation is said to occur when a causal effect of some variable X on an outcome Y is explained by some intervening variable M. The authors recommend that with small to moderate samples, bootstrap methods (B. Efron & R. Tibshirani, 1993) be used to assess mediation. Bootstrap tests are powerful because they detect that the sampling distribution of the mediated effect is skewed away from 0. They argue that R. M. Baron and D. A. Kenny's (1986) recommendation of first testing the X --> Y association for statistical significance should not be a requirement when there is a priori belief that the effect size is small or suppression is a possibility. Empirical examples and computer setups for bootstrap analyses are provided.

Reconsidering Baron and Kenny: Myths and Truths about Mediation Analysis

Abstract: Baron and Kenny’s procedure for determining if an independent variable affects a dependent variable through some mediator is so well known that it is used by authors and requested by reviewers almost reflexively. Many research projects have been terminated early in a research program or later in the review process because the data did not conform to Baron and Kenny’s criteria, impeding theoretical development. While the technical literature has disputed some of Baron and Kenny’s tests, this literature has not diffused to practicing researchers. We present a nontechnical summary of the flaws in the Baron and Kenny logic, some of which have not been previously noted. We provide a decision tree and a step-by-step procedure for testing mediation, classifying its type, and interpreting the implications of findings for theory building and future research.